1. Field of the Invention
The present invention relates to a mechanism for conveying a sheet on which an image is formed, to a discharge tray in an image forming apparatus such as a copier, a printer, a facsimile apparatus or the like.
2. Description of the Related Art
Conventionally, there is provided an image forming apparatus such as a copier or a printer, provided with reversing means which serves as a mechanism to reverse a sheet, in order to discharge the sheet processed by the image forming apparatus, with directing the front face of the sheet upward or downward, as disclosed in Japanese Unexamined Patent Publication JP-A 5-310357 (1993).
This image forming apparatus will be described with referring to FIG. 7. A main unit 81 of the image forming apparatus comprises: an exposing and reading section 82 which is disposed in an upper portion of the image forming apparatus main unit 81 and which reads an original; a scanning section 83 which is disposed under the exposing and reading section 82; a developing section 84 which is disposed under the scanning section 83; a sheet housing section 85 which is disposed under the developing section 84; and sheet discharging means 86 which is disposed to a side of the developing section 84 and the sheet housing section 85.
The sheet discharging means 86 includes a first discharge port 87 from which a sheet is discharged without being reversed, and a second discharge port 88 from which a sheet is discharged with being reversed. On the side of the image forming apparatus main unit 81, a first discharge tray 89 corresponding to the discharge port 87, and a second discharge tray 90 corresponding to the discharge port 88 are respectively disposed.
A sheet whose front face is directed upward is discharged to the first discharge tray 89, and a sheet whose back face is directed upward is discharged to the second discharge tray 90.
Another image forming apparatus is disclosed in Japanese Examined Patent Publication JP-B2 6-69862 (1994). In the image forming apparatus, as shown in FIG. 8, a sorter 92 is disposed to a side of an image forming apparatus main unit 91. The sorter 92 includes a non-sort discharge roller pair 93 which is not used in a sorting operation, and a sort discharge roller pair 94 which is used in a sorting operation. The sorter has a non-sort bin (discharge tray) 95 to which a sheet is discharged from the non-sort discharge roller pair 93, and sort bins (discharge trays) 96a, 96b, and 96c to which a sheet is discharged from the sort discharge roller pair 94.
A sheet which is not sorted is discharged to the non-sort bin 95, and a sheet which is sorted is discharged to the sort bin 96a, 96b, or 96c.
Even when front-face-discharged and back-face-discharged sheets are mixedly placed on the same single discharge tray, the user can easily distinguish the sheets based on the direction of their image forming faces, because front-face-discharged sheets are placed with upward directing their image forming faces and back-face-discharged sheets are placed with downward directing their image forming faces. Since the user usually removes non-sort-discharged sheets and sort-discharged sheets immediately after a discharging operation, provided that no sheet remains, there arises no problem even when a sheet is discharged after removing sheets.
In other words, even when sheets are discharged to discharge trays of the same kind, the sheets can be distinguished without producing any particular inconvenience. However, the provision of discharge trays of two kinds requires useless discharge trays, and increases the number of parts and the production cost.
In the discharge trays of two kinds, the distance between a discharge tray of one kind disposed in a lower position and a discharge tray of the other kind disposed in an upper position is limited. Therefore, the number of sheets which can be housed in the former discharge tray is restricted.